                 \begin{tabular}{l*{4}{c}} \hline \hline \noalign{\smallskip}                                 & \multicolumn{2}{c}{U.S. Colleges}                                  & \multicolumn{2}{c}{Non-U.S. Colleges} \\                                          \cmidrule(l){2-3} \cmidrule(l){4-5}                                 & \multicolumn{1}{c}{U.S. Worker}                                  & \multicolumn{1}{c}{Non-U.S. Worker}                                  & \multicolumn{1}{c}{U.S. Worker}                                  & \multicolumn{1}{c}{Non-U.S. Worker} \\          
\hline \noalign{\smallskip}
Standardized z-score for GPA&    0.049\sym{***}&    0.053\sym{***}&    0.029\sym{***}&    0.048\sym{***}\\
                &  (0.001)         &  (0.012)         &  (0.005)         &  (0.006)         \\
[1em]
Years of experience&    0.066\sym{***}&    0.129\sym{***}&    0.052\sym{***}&    0.155\sym{***}\\
                &  (0.001)         &  (0.009)         &  (0.004)         &  (0.004)         \\
[1em]
Years of experience\string^2 / 100&   -0.137\sym{***}&   -0.330\sym{***}&   -0.073\sym{***}&   -0.369\sym{***}\\
                &  (0.003)         &  (0.051)         &  (0.021)         &  (0.015)         \\
\hline \noalign{\smallskip} 
N               &   177833         &     2076         &    14677         &    49443         \\
Adjusted R$^2$  &     0.28         &     0.36         &     0.24         &     0.39         \\
                 \hline \hline \noalign{\smallskip}                 \end{tabular}         
